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Alpha-Fetoprotein (AFP), Amniotic Fluid — Immunoassay, Concentration

Published: August 9, 2026Updated: August 16, 2026

Measures alpha-fetoprotein in amniotic fluid to help evaluate certain suspected fetal abnormalities, especially open neural tube defects.

Quick summary

["Amniotic fluid AFP is a specialized prenatal test that may help evaluate suspected fetal abnormalities but must be interpreted with other findings."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
83074-5
Short code
AFP Amn IA-aCnc
Synonyms
AFP Amn IA-aCnc
Category
liver
Sample
fluid
Container
Sterile tube
Units
N/A
Ref low
0
Ref high
10
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82105
SNOMED
394971007
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What is this test?

Alpha-fetoprotein (AFP) is a protein made by the developing fetus. This test measures the concentration of AFP in fluid surrounding the fetus.

Why might I need this test?

Amniotic fluid AFP may be measured when a clinician needs additional information about a suspected fetal abnormality, particularly an open neural tube defect, abdominal wall defect, or another condition associated with abnormal AFP levels.

How is the test performed?

A small sample of amniotic fluid is collected during amniocentesis, usually with ultrasound guidance. The laboratory then uses an immunoassay to measure the AFP concentration in the sample.

How do I prepare for the test?

No fasting or medication changes are generally required for the laboratory measurement itself. Because the sample is obtained during amniocentesis, follow your obstetric clinician's instructions about consent and procedure-specific preparation.

Reference range

Normal: <10 ng/mLN/A

Specimen: fluid

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Amniotic fluid AFP

Frequently asked questions

Is amniotic fluid AFP the same as the maternal serum screening test?
No. The maternal screening test measures AFP in the mother's blood, while this test measures AFP in the fluid around the fetus.
How is amniotic fluid obtained?
A clinician removes a small amount of amniotic fluid during amniocentesis, generally using ultrasound guidance. The fluid is then sent to a laboratory for analysis.
Does an abnormal AFP result mean the fetus has a birth defect?
No. An abnormal AFP result indicates that further evaluation may be needed, but it does not establish a diagnosis by itself. Imaging and other prenatal test results are considered alongside AFP.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy